A railcar typically adopts a dual structure constituted by a bodyshell and an interior member provided at an interior side of the bodyshell. The bodyshell is formed by welding metal, such as stainless steel or aluminum. Therefore, welding distortion occurs at the bodyshells in a manufacturing process, so that size differences among the bodyshells are comparatively large. Further, since the interior member is attached to an internal frame configured at the interior side of the bodyshell, the interior member has to be a member that is easy for a worker to attach and handle. To, for example, secure a wide interior space, a thin member is used as the interior member in many cases. In order that an internal size of the driver's cab becomes constant, a liner having an appropriate thickness is inserted between the internal frame and the interior member.
A large number of devices, such as a control device, are arranged in the driver's cab. These devices are attached to the internal frame of the bodyshell. However, the position of the internal frame may be displaced from a predetermined position by the welding distortion. In this case, it is necessary to, in manufacturing steps, make screw holes with a tap and adjust the positions of attachment holes of machinery and the positions of the screw holes. As above, there are problems that: the welding distortion of the bodyshell of the narrow driver's cab to which a large number of devices are attached significantly affects the steps; and it is difficult to perform efficient manufacturing work.
Here, PTL 1 proposes a railcar manufacturing method by which an entire carbody is formed in such a manner that: a driver's cab unit including the driver's cab of the carbody and a tip end portion of the railcar is separately formed; and this driver's cab unit is combined with the other portion of the carbody. According to this manufacturing method, the cost reduction can be realized by the rationalization of the work.